Dr Hansen developed a perifusion system for the study of gonadotropin releasing hormone (GnRH)-stimulated luteinizing hormone (LH) release from dispersed rat pituitary cells. Using this system, it was possible to identify a previously unrecognized role for intracellular-derived calcium (Ca2+) during GnRH-stimulated LH release. The role of intracellular Ca2+ in the gonadotrope is of great interest because of its possible involvement in the mechanism that regulates the movement of extracellular Ca2+ into the gonadotrope. Extracellular Ca2+ flux into the gonadotrope is essential for sustained LH release, which is necessary for normal reproductive function. In order to test the hypothesis that receptor- stimulated metabolism of inositol phospholipids and intracellular Ca2+ mobilization are coupled and involved in the influx of extracellular Ca2+. Dr Hansen will perform experiments in dispersed cells from the ovine pars tuberalis. This naturally enriched population of gonadotropes will facilitate measurement of cytosolic free Ca2+ levels using fura-2 and identification of inositol phospholipid metabolites by high performance liquid chromatography (HPLC). These studies may improve our understanding of the cellular mechanisms that underlie the effectiveness of GnRH analogs in the treatment of central precocious puberty.